1. Field of Invention
The bearing carrier puller improvements disclosed in this document provide a simplified method of removing a bearing carrier from a Mercruiser lower gear case, thus minimizing the risk of damage to a lower gearcase during removal of its' bearing carrier. The advantage of this tool over the prior art is that a mechanic's helper, with minimal skills, can perform the otherwise difficult task of removing a bearing carrier, thus reducing the work load on the mechanic.
The lower gear case of a marine drivetrain is subject to substantial abuse. Impact with submerged obstacles and the bottom, operator error, and poor maintenance all contribute to a triving repair industry.
Unfortunately, the use of recreational marine craft is largely a seasonal pursuit, resulting in a cyclical income stream for most marine mechanics. During the boating season, a marine mechanic is inundated with urgent repair orders. However, as the weather cools, the mechanic's income depends on the foresight of experienced customers who realize that the off season is the time to schedule boat work. Consequently, the permanent staffing at a marine repair shop will be the number of people who can be financially supported by the work generated in the off season. When the work load picks up in the boating season and the work capacity of the permanent staff is exceeded, delays are unavoidable. Mechanics are reluctant to invest their time and risk their customer's property to train temporary help. Therefore, work that requires more than rudimentary skills waits in line for the skilled permanent staff.
With an eye to efficient and effective completion of repair orders during the busy boating season, it is of particular advantage to marine repair shops to simplify as many tasks as possible to a level that may be performed by unskilled help. Bearing carrier removal is a tricky task that is reduced to a rudimentary skill level with the improvements that we have made to Barrow's Bearing Carrier Puller for Outboard Motors, U.S. Pat. No. 4,236,291, issued in 1980.
2. Discussion of Prior Art
Marine mechanics currently use the following tools to remove bearing carriers from lower gear cases:
A common method of removing a bearing carrier is to insert a gear puller into the bearing carrier, grip it at the edge and bear against the propeller shaft to dislodge the bearing carrier. This procedure has two distinct disadvantages: pulling the edge of the bearing carrier may cause it to crack and fail, compounding the service problem; and bearing against the propeller shaft to dislodge the bearing carrier may press the shaft into the housing rather than withdraw the bearing carrier, again exacerbating the problem.
A second method of removing a bearing carrier is to use a Bob Kerr tool. Kerr was issued U.S. Pat. No. 3,846,898 for this tool in 1974. This tool grips the bearing carrier with a pair of hooks and bears against the propeller shaft to dislodge the bearing carrier. As in the case of a gear puller, there is a risk of driving the propeller shaft instead of pulling the bearing carrier. It is a good tool, but it requires a knowledgable hand.
A third method of removing a bearing carrier is to use Randy Barrow's Bearing Carrier Puller of Outboard Motors. Barrow was issued U.S. Pat. No. 4,236,291 for this tool in 1980. This is a very well designed tool that is almost idiot proof. This tool consists of: a block which provides a bearing against the gear case; a boss that secures the propeller shaft relative to the block; a handle extending from the boss to rest against the gear case; and a nut that is rotated to extract the boss, propeller shaft, and bearing carrier as one unit from the gear case. However, this tool requires a skilled operator because improper use may result in a bent gear shifter, compounding the service problem. The novelty disclosed in the claims of the present document are improvements to this tool that overcome this failing.
A fourth method of removing a bearing carrier is to use Precision's propeller and bearing carrier puller. Francis Klucz and Norm Brunet were issued U.S. Pat. No. 4,864,709 for this tool in 1989. This tool grips the bearing carrier and bears against the propeller shaft similar to Kerr's tool. This is also a very good tool, but like Kerr's tool or a gear puller, it's requires skill to use properly.
A fifth method of removing a bearing carrier is to use Cochran's bearing carrier puller. Danny Cochran, a marine mechanic in Flowery Branch, Georgia, applied for a patent on his bearing carrier puller in 1996 (approx.), and has been making and selling his tool since 1997. This tool is similar to Barrow's, it consists of: a block which bears against the gear case; and a Torrington bearing, which is placed between the block and a nut on the propeller shaft. It dislodges the bearing carrier and propeller shaft as one unit when the nut is rotated on the propeller shaft. The differences between Cochran's and Barrow's tools are: Cochran's tool includes gripping means that engage the splines of the propeller shaft to check rotation of the shaft; Cochran's tool includes a Torrington bearing to reduce friction between the block and the prop nut; Barrow's tool includes a boss that engages the propeller shaft and in turn, travels by rotation of a nut; a handle extends from the boss on Barrow's tool; Barrow's tool also includes surface features that enhance use of the tool with several housing sizes, whereas Cochran's tool is designed to engage a single housing size.